Laboratory devices, in particular for chemical, medical, and biological applications, typically have a housing which encapsulates the devices. The housing is predominantly used so that the hazard potential which is intrinsic to such devices is kept low for the operator and the surrounding structures. The housing may be implemented as explosion-proof, for example. With centrifuges which rotate at moderate and high speeds, a large hazard potential arises from the rotors, whose kinetic energy is suddenly released in case of a rotor fracture. Therefore, the housings for laboratory devices and the like have been the subject of intensive development work for years.
A housing of the relevant type has a housing bottom part and at least one housing cover, which is typically implemented integrally. Such a housing is known, for example, from DE 100 17 314 A1.
The cover closure has an essential significance. On the one hand, the housing cover must be held closed by high forces, on the other hand, the opening and closing of the cover is to be able to be performed with little effort and in the shortest possible time. In addition, the components of the cover closure are to be situated in such a way that they are not significantly damaged in case of an accident. In the event of a malfunction, the affected laboratory device is to be able to still be opened after shutdown. A further requirement is that the closure mechanism is not to occupy excessive installation space and is additionally to be as wear-free, low maintenance, and thus reliable as possible.
Cover closures according to the prior art are also known, for example, from Patent Specifications EP 0 819 471 A1, DE 40 25 134 C1, and EP 1 136 745 A2.
There is a need to provide a low-maintenance cover closure for a housing cover of a laboratory device and the like which is simple to operate. There is also a need to provide such a cover closure in which high retention forces may be implemented with comparatively low installation space.
According to one embodiment of the present invention, the cover closure has a closure hook, which is mounted on an eccentric so it is pivotable and/or rotatable and is only movable translationally into the closing position by rotation of the eccentric, after it has engaged in a closure element belonging to the housing cover, which is preferably performed by rotation by a specific angle around the pivot axis.
The closing using the cover closure is performed in two phases. In the first phase, the closure hook engages in at least one corresponding closure element on the housing cover, such as a cover hook. In a second phase, the closure hook is moved translationally in the closing direction, the housing cover being pulled closed with high force until finally a final closing position is reached. The two phases may also overlap in time. The translational movement of the closure hook occurs via an eccentric on which the closure hook is simultaneously mounted so it is pivotable.
In the meaning of the present invention, an eccentric is understood as a cam or disk cam, whose area center of gravity or centerpoint is not coincident with the axis of rotation. The centerpoint is accordingly outside the axis of the driving shaft. Rotational movements may thus be converted into translational movements (and vice versa). The eccentricity is a measure of the spacing of centerpoint and axis of rotation. The mechanical lever laws apply for the generated and transmitted forces and torques.
An extremely compact construction for the cover closure according to one embodiment of the present invention advantageously results in this way, so that it may be situated without problems on a housing bottom part, preferably integrated in the housing wall. High closing forces may simultaneously be generated, which securely close the housing cover. In addition, the cover closure according to one embodiment of the present invention may be operated largely automatically, which additionally increases in the safety.
In an advantageous refinement of the cover closure according to one embodiment of the present invention, the eccentric has a circular outline, whereby an especially good pivot connection to the closure hook results. In addition, the eccentric is situated eccentrically and/or asymmetrically on an eccentric driveshaft, which rotationally drives the eccentric. Due to the offset of eccentric centerpoint and driveshaft linkage point, an eccentricity is formed which decisively causes the translational movement of the closure hook.
In addition, according to another aspect, the closure hook is guided using a pin and/or guide pin in a crank, whereby the movement path for the closure hook is predefined and may advantageously be restricted in its degrees of freedom. In addition, the safety is increased, because the crank additionally retains the closure hook if a malfunction occurs on the laboratory device. The crank is preferably situated on a central retention and guide plate.
According to another refinement, the closure hook has a guide section (and/or guide path or contour), which optionally works together with a guide pin on a central retention and guide plate to move the closure hook into an opening position, i.e., a position which releases the housing cover.
In yet another refinement, the closure hook is pre-tensioned spring-loaded, i.e., using a spring, into the engaging pivot position, in which it engages in the corresponding closure element on the housing cover.
According to a further refinement, the closure hook is equipped with a slide guide or bevel, on which the corresponding closure element of the housing cover, such as a corresponding cover hook, may slide during closing of the housing cover and preferably pivot the closure hook, whereby simple closing of the housing cover preferably results.
Furthermore, in one embodiment, a motor drive is included which drives the eccentric using an eccentric driveshaft, whereby on the one hand defined closing forces may be generated and on the other hand the closing and/or opening may be performed largely automatically. For such automation, it is also advantageous if at least one cam lug is situated on the eccentric, which actuates at least one micro-switch to allow a rotational angle control. In this way it is also possible to detect a position of the closure hook.
To also be able to loosen the cover closure manually after occurrence of a malfunction or in the event of power loss, for example, according to another refinement, at least the closure hook, as well as its eccentric together with the drive, are situated on a rocker, which is fastened around a point of rotation on the retention and guide plate. A latch may be provided to release and/or block the rocker in relation to the retention and guide plate. The rocker is advantageously retained and/or released in position loaded by a rotational spring using this latch. In addition, it is advantageous if the latch and the closure hook are connected via a coupling element. This is accordingly a so-called emergency unlocking latch having coupling part.
The invention is explained in greater detail hereafter on the basis of an exemplary embodiment in connection with the figures.